Hexosaminidase B (beta polypeptide)
PDB rendering based on 1nou.
Available structures
PDB Ortholog search: PDBe, RCSB
Symbols  ; ENC-1AS; HEL-248
External IDs ChEMBL: GeneCards:
EC number
RNA expression pattern
Species Human Mouse
RefSeq (mRNA)
RefSeq (protein)
Location (UCSC)
PubMed search

Beta-hexosaminidase subunit beta is an enzyme that in humans is encoded by the HEXB gene.[1][2][3] Hexosaminidase B is the beta subunit of the lysosomal enzyme beta-hexosaminidase that, together with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules containing terminal N-acetyl hexosamines. Beta-hexosaminidase is composed of two subunits, alpha and beta, which are encoded by separate genes. Both beta-hexosaminidase alpha and beta subunits are members of family 20 of glycosyl hydrolases. Mutations in the alpha or beta subunit genes lead to an accumulation of GM2 ganglioside in neurons and neurodegenerative disorders termed the GM2 gangliosidoses. Beta subunit gene mutations lead to Sandhoff disease (GM2-gangliosidosis type II).[3]


  1. ^ O'Dowd BF, Quan F, Willard HF, Lamhonwah AM, Korneluk RG, Lowden JA, Gravel RA, Mahuran DJ (Apr 1985). "Isolation of cDNA clones coding for the beta subunit of human beta-hexosaminidase". Proc Natl Acad Sci U S A 82 (4): 1184–8.  
  2. ^ Korneluk RG, Mahuran DJ, Neote K, Klavins MH, O'Dowd BF, Tropak M, Willard HF, Anderson MJ, Lowden JA, Gravel RA (Jul 1986). "Isolation of cDNA clones coding for the alpha-subunit of human beta-hexosaminidase. Extensive homology between the alpha- and beta-subunits and studies on Tay-Sachs disease". J Biol Chem 261 (18): 8407–13.  
  3. ^ a b "Entrez Gene: HEXB hexosaminidase B (beta polypeptide)". 

Further reading

  • Mahuran DJ (1991). "The biochemistry of HEXA and HEXB gene mutations causing GM2 gangliosidosis.". Biochim. Biophys. Acta 1096 (2): 87–94.  
  • Mahuran DJ (1999). "Biochemical consequences of mutations causing the GM2 gangliosidoses.". Biochim. Biophys. Acta 1455 (2-3): 105–38.  
  • Gilbert F, Kucherlapati R, Creagan RP, et al. (1975). "Tay-Sachs' and Sandhoff's diseases: the assignment of genes for hexosaminidase A and B to individual human chromosomes.". Proc. Natl. Acad. Sci. U.S.A. 72 (1): 263–7.  
  • McInnes B, Potier M, Wakamatsu N, et al. (1992). "An unusual splicing mutation in the HEXB gene is associated with dramatically different phenotypes in patients from different racial backgrounds.". J. Clin. Invest. 90 (2): 306–14.  
  • Bolhuis PA, Bikker H (1993). "Deletion of the 5'-region in one or two alleles of HEXB in 15 out of 30 patients with Sandhoff disease.". Hum. Genet. 90 (3): 328–9.  
  • Wakamatsu N, Kobayashi H, Miyatake T, Tsuji S (1992). "A novel exon mutation in the human beta-hexosaminidase beta subunit gene affects 3' splice site selection.". J. Biol. Chem. 267 (4): 2406–13.  
  • Banerjee P, Siciliano L, Oliveri D, et al. (1992). "Molecular basis of an adult form of beta-hexosaminidase B deficiency with motor neuron disease.". Biochem. Biophys. Res. Commun. 181 (1): 108–15.  
  • Boose JA, Tifft CJ, Proia RL, Myerowitz R (1992). "Synthesis of a human lysosomal enzyme, beta-hexosaminidase B, using the baculovirus expression system.". Protein Expr. Purif. 1 (2): 111–20.  
  • Mahuran DJ (1990). "Characterization of human placental beta-hexosaminidase I2. Proteolytic processing intermediates of hexosaminidase A.". J. Biol. Chem. 265 (12): 6794–9.  
  • Neote K, McInnes B, Mahuran DJ, Gravel RA (1990). "Structure and distribution of an Alu-type deletion mutation in Sandhoff disease.". J. Clin. Invest. 86 (5): 1524–31.  
  • Neote K, Brown CA, Mahuran DJ, Gravel RA (1991). "Translation initiation in the HEXB gene encoding the beta-subunit of human beta-hexosaminidase.". J. Biol. Chem. 265 (34): 20799–806.  
  • Dlott B, d'Azzo A, Quon DV, Neufeld EF (1990). "Two mutations produce intron insertion in mRNA and elongated beta-subunit of human beta-hexosaminidase.". J. Biol. Chem. 265 (29): 17921–7.  
  • Nakano T, Suzuki K (1989). "Genetic cause of a juvenile form of Sandhoff disease. Abnormal splicing of beta-hexosaminidase beta chain gene transcript due to a point mutation within intron 12.". J. Biol. Chem. 264 (9): 5155–8.  
  • Hubbes M, Callahan J, Gravel R, Mahuran D (1989). "The amino-terminal sequences in the pro-alpha and -beta polypeptides of human lysosomal beta-hexosaminidase A and B are retained in the mature isozymes.". FEBS Lett. 249 (2): 316–20.  
  • Bikker H, van den Berg FM, Wolterman RA, et al. (1989). "Demonstration of a Sandhoff disease-associated autosomal 50-kb deletion by field inversion gel electrophoresis.". Hum. Genet. 81 (3): 287–8.  
  • Bolhuis PA, Oonk JG, Kamp PE, et al. (1987). "Ganglioside storage, hexosaminidase lability, and urinary oligosaccharides in adult Sandhoff's disease.". Neurology 37 (1): 75–81.  
  • Proia RL (1988). "Gene encoding the human beta-hexosaminidase beta chain: extensive homology of intron placement in the alpha- and beta-chain genes.". Proc. Natl. Acad. Sci. U.S.A. 85 (6): 1883–7.  
  • Mahuran DJ, Neote K, Klavins MH, et al. (1988). "Proteolytic processing of pro-alpha and pro-beta precursors from human beta-hexosaminidase. Generation of the mature alpha and beta a beta b subunits.". J. Biol. Chem. 263 (10): 4612–8.